Magnetic compass



C. H. COLVIN MAGNETIC COMPASS Filed Oct. 11. 1922 Aug. 7, 1928.

UNITED STATES PATENT OFFICE.

enemies H. COLVIN, or B COMPANY, A cormz'rn'ansnrr ROOKLYN, NEW YORK,ASSIGN'OR TO PIONEER INSTRUMENT GONSISTING OF CHARLES H. COLVIN, BEIGEH.

GOLDSBOBOUGH, AND MORRIS M. TITTERINGTON, OF BROOKLYN, NEW YORK.

Application filed October 11, 1922. Serial No. 593,696.

invention relates passes,

MAGNETIC compassto magnetic comand more particularly to themagneticelements of compasses of the movlng card type. my drawings Themagnetic and described in the following element shown m paragraphs is ofthe general form disclosed 1n my Patent #1,33 1,27 3 issued March 16,1920. The improvements made are not lunited, however,

An object of my to this type of compass.

invention is the improvement of the magnetic element of a compass, andof its mounting. Further objects are to make such a magnetic elementeasy to construct,-lig'ht, in weight and. of low speclfic gravity,strong enough to be easily handled in manufacturing, well damped in itsoscillations when submerged in liquid, and secure in its mounting. Othertages will appear as the after disclosed.

objects and advaninvention 1s herein- Referring to the drawings, whichillus tratewhat I now consider a preferred form of this invention:

Figure 1 represents a top view of the magnetic element and support,

Figure 2 section, as at 2-2 in Figure 3 represents section, as atrepresents a inverted cup upon side view, partly in Figure 1, and a sideview, 3-3 in'Figure 1.

Referring to the drawings, part which are marked the partly in 11 is ancompass cardfi 12 and 13. The cup is preferably of a cellulose material,such as is commonly known as lin. The cards are thereon while and thispart (11) cup as shown; ma be pivot bushing 17 part-11 is in fiat isthen formed into a The markings of the card painted with radio-activematerial to render them visible at ni Part 14 is a carrier to celluloidor pyrapreferably prmted sheet form,

%lta w 'ch is attached 15 and 16, and the he cup 11 is removablyattached by means of the screws 18.

The

magnets are clamped or soldered in place,

and the bushing 1 is riveted or soldered or both. At the lower end ofthe bushing 17 is attached the center of the the cup 19 forms a part.The jewel bearing rests is secured in part the hemispherical cup 19. Inbushing 17 is fastened the pivot 20, whose point approximately cideswith the center of the sphere 0 coin- Wl'llCh 21 in which part 20 22which acts as a .the liquid 35, which is troleum or asphalt base plungerin' socket 23.- The plunger 22 is supported on a spring 24 and hasextending from its lower end a wire 25 the extremity of which is bent atright angles, lying in a slot 26 in the end of the socket 23. A hole 27communicates from the spring chamber in socket 23 to the outside.

At the upper end of part 22 is a jewel cap 28. Below and 29 are securedsolidly to part 22. To collar 29 are removably attached retainers 30 and31, by means of screws 32.

At 34 is shown a fragment of the compass bowl to which socket 23 isattached. The entire magnetic element is surrounded with contained inthe or a similar peproduct, is a precompass bowl. Kerosene,

ferred liquid.

' In a magnetic compass it is important if not essential that both theabsolute weight, and the net weight on the pivot (the difference betweenthe two being due to the buoyant'efi'ect of the liquid) be kept at aminimum, with the magnets as the major item of weight. It is alsoparticularly desirable to keep the moment of inertia of the element aslow as possible: .that is, it is important to reduce the weight of thoseparts which are at the greatest distance from the center. This isaccomplished by luloid cup 11, the specific gravityof which is of thenature of 1.4 as compared to water.

The specific gravity of the filling liquid (say,

kerosene) is approximately 0.7, which there fore reduces the effectiveweight of the cup by one-half. Since this cup comprises the J onlystructure at a distance from the center,

high. 1

he carrier 14 constitutes an improvement in construction, as it providesin a single element a means of inter-connecting the magnets, cards andpivot. 1

Parts 19, 30 and 31, in combinationwith the pivot 20 and jewel 21'provide a means of preventing the magnetic element from becomingdisassociated from the mounting ost.

The jewel cap 28, in combination with the above elements, acts as aguide for the pivot 20, and assures its contact with the polished thisis a collar 29. Both 28' the use of the cel- I claim as new is:

Claims: y

1. In amagnetic compass, in combination, a magnetic element, andsupporting means for said magnetic element: comprising a plunger, acup-bearing mounted therein, a

socket in which said plunger is carried, elastic means between saidplungerand said socket, a axial extension on said plunger terminati g ina positioning element, an extension on said socket member terminating ina slot in which said positioning element is contained, and said sockethaving a pas sage connecting from the inside to the outside of saidsocket.

2. In a magnetic compass, in combination, a magnetic element, andsupporting means for said magnetic element: comprising a plunger acup-bearing mounted therein, a

' socket 1n which said plunger is carried,

elastic means. between said plunger and socket, an axial extension onsaid plunger terminating in a positioning element, and an extension onsaid socket member terminating in a slot in which said positioningelement is contained.

3. In a magnetiecompass, in combination; a magneticelein'ent, comprisinga cup composed ofcellulose material, indicating cards markedthereon,n1agnets, pivoting means, a

supporting member connecting said cup,

magnets and pivotingmeans, means for re- 'movably attaching said cup tothe supporting member, means for attaching said pivot ing member to thesupporting member; supporting means for the entire magnetic element,comprising a-plunger, a cup-bearing mounted therein, a socket in whichsaid plunger is carried, elastic means between said plunger and saidsocket, an extension on said plunger terminating in a positioningelement, an extension on said socket member.

terminating in a slot in which said'positioning element may becontained, sald socket having a'passage communicatingfrom the socketchamber to the outside of the socket;

and retaining means, comprising in combination with the before-mentionedpivoting means and cup-bearing, a cup attached to the pivot andsubstantially concentric therewith, covers attached to said plunger forretaining said cup means for guiding "said pivot into saidcup-bearing;and a liquid.

contained in said compass, and surrounding the above mentioned elements.4

A. A magnetic compass comprising in combination, a magnetic element,means including a pivot and bearing for supporting said element,retaining means for said element, said retaining means comprising a cupattached-to said pivot and substantially concentric therewith, and aplurality ofcovers attached to said supporting means for retaining saidcup.

5. A magnetic compass comprising in combination, a magnetic element,means including a pivot and bearings for supporting said element,retaining means for said element, said retaining means comprising a cupattached to said pivot and substantially concentric therewith, aplurality of covers attached to said supporting means for retaining saidcup, and means for guiding said pivot. into said bearing.

6. A magnetic compass comprising in combination, a-magnetic elementincluding a cellulose cup having two cards, permanent magnet meansconnected to said cup, means including a pivot and support therefor forsupporting said magnetic element, a second cup secured to said pivot andsubstantially concentric therewith, and retaining covers attached tosaid support and surrounding said second mentioned cup.

7. A magnetic compass comprising in combination, a magnetic elementhaving two cards, permanent magnet means connected to said cards, asupport, means pivotally mounting said element upon said support, a cupattached to said pivotally mounting means and substantially concentrictherewith, and covers attached to said support for retaining said cup.

8. A magnetic compass comprising in combination, a support post, a pivotresting thereon, an arched carrier straddling the pivot and post andfixed to the pivot, parallel arms integral with the arched carrierextendingdownward to either side of the post, a fiat rest integral withthe arched carrier and each arm, a compass card centrally apertured anddisposed on 'the'flat rests with the arched carrier projecting upthrough the card, and magnets carried by the arms.

' 9. A magnetic compass comprising in combination, a support post, apivot resting thereon, an arched carrier straddling the pivot and postand fixed to the pivot, a pair of cooperating retainer cups movablerelatively to each other but connected and held together againstseparation,means attaching one cup to the arched carrier, meansconnecting the other cup .to the post, parallel arms integral with thearched carrier extending downward to either side of the post, a flatrest integral with the arched carrier and each arm, a compass cardcentrally apera combination, a compass indicating means, a '11. Acompass as tured and disposed on the fiat rests with the duced indiameter to prevent withdrawal of arched carrier projecting-up throughthe said inverted member et permit universal 15 card, and magnetscarried by the arms. 1 freedom of movement between the inverted 10. Amagnetic compass comprising in member and upstandintg1 device.

de ned in claim 10 furpost supporting the indicating means, a therrestricted by making the said upstandpivot interposed between theindicating ing cup-shaped device in a plurality of 20 means and thepost, an inverted hemispherisections. cal member fixed on the indicatingmeans Signed at Brooklllyn, in the county of and embracing the pivot, anupstanding cup- Kings and State of ew York this 10th day shaped devicefixed on the post embracin of October, A. D. 1922. the invertedhemispherical member, and sai upstanding cup having its upper rim re-CHARLES COLVIN.

